Omni-directional transmitting &amp; receiving antenna

ABSTRACT

There is disclosed an omni-directional transmitting and receiving antenna which, in the preferred embodiment, is particularly suitable for use on the ship to shore marine frequencies. The antenna comprises a non-conductive hollow outer shell; a first substantially circularly shaped conductive element located within the outer shell and wherein the first conductive element contains a discontinuity; a second circularly shaped continuous conductive element located within the outer shell adjacent to and coaxially with the first conductive element; and a first means for electrically connecting the first conductive element to the second conductive element.

United States Patent n 1 Herbert 451 July 10, 1973 OMNI-DIRECTIONAL TRANSMITTING &

RECEIVING ANTENNA [75] inventor: Lawrence W. Herbert, Lindenhurst,

Ill.

Primary ExaminerEli Lieberman Attorney-Hume, Clement, Hume & Lee

[ 5 7 ABSTRACT There is disclosed an omni-directional transmitting and receiving antenna which, in the preferred embodiment, is particularly suitable for use on the ship to shore marine frequencies. The antenna comprises a nonconductive hollow outer shell; a first substantially cir' 52 us. Cl 343/742, 343 743, 343/873 eulerly shaped conductive element located within h 51 1m. (:1. H01q 11 12 outer shell and wherein the first conductive element [58] Field of Search 343/743, 842, 873, contains a discontinuity; a second circularly shaped 343 742 continuous conductive element located within the outer shell adjacent to and coaxially with the first con- [56] a R fer n e Cit d ductive element; and a first means for electrically con- UNITED STATES PATENTS necting the first conductive element to the second con- 3,266,042 8/1966 Mahoney et al. 343 743 duct've element 3,299,430 1/1967 Huber et a] 343/873 2 Claims, 4 Drawing Figures OMNI-DIRECTIONAL TRANSMITTING & RECEIVING ANTENNA BACKGROUND OF THE INVENTION The present invention relates to antennas and more particularly to an improved omni-directional antenna for use with a marine transmitter or marine receiver.

In the field of marine radio operation, it is currently the practice to employ an antenna which is polarized vertically only. It has thus been the general practice to employ whip antennas for marine transmitters and receivers since the whip antenna has this characteristic.

Although such antennas have served the purpose, they are subject to certain limitations. Because they are exposed, they are subjected to the corrosive elements present in marine navigation and furthermore, under certain circumstances, the signal strength received or sent by these antennas has not proved satisfactory.

In an attempt to overcome these limitations, several different types of antennas have been utilized. For example, a double-halo antenna has been utilized. For example, it has been well known to utilize double-halo antennas. A double-halo antenna normally comprises two substantially circular conductive elements mounted vertically with respect to each other on a rigid mast. Each of the substantially circular conductive elements contains a discontinuity therein. With this discontinuity, the circular element is simply a folded dipole with the ends capacitively loaded to reduce the overall length. Normally, the upper conductor is made of a first conductive material while the'lower conductor is made of a smaller diameter second conductive material. This double-halo is mounted on a mast and does not contain any outside housing. This type of antenna has two drawbacks. First, it is subjected to the effects of metallically corrosive elements and second, because this type of antenna is only horizontally polarized and when placed in'an orientation other than horizontal, there is a substantial falloff in the signal strength of the antenna.

The present invention, however, finds specific applicability in the field of ship to shore marine frequency transmission and reception. The present invention is both horizontally and vertically polarized and combines the favorable characteristics of the whip antenna, the halo antenna and the enclosed omni-directional antennas described above, and does not possess any of the aforedescribed limitations.

SUMMARY OF THE INVENTION The general purpose of this invention is to provide an antenna suitable for ship toshore marineuse which embraces all of the advantages of similarly employed antennas and possesses none of the aforedescribed limitations. To attain this, the present invention contemplates a unique double-halo arrangement which is fully enclosed in a non-conductive hollow outer housing. The antenna comprises a non-conductive hollow outer shell containing two substantially circularly shaped tubular conductive elements therein. One of the circular elements forms a complete ring-shaped circle while the second of these elements has a discontinuity therein. The-element with the discontinuity is arranged to be the upper element of the halo grouping. Both elements, in the preferred embodiment, are manufactured from the same conductive material. A rigid means is provided for electrically connecting the first conductive element to the second conductive element and the electrical connection is made adjacent to the discontiand a non-conductive cover is placed over the opening of the hollow shell, thereby making the antenna impervious to all corrosive elements.

It is, therefore, an object of the present invention to provide an omni-directional antenna which is polarized both vertically and horizontally.

Another object is to provide an antenna which is suitable for use on the ship to shore marine frequencies.

Still another object is to provide an antenna which is impervious to metallically corrosive elements.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the exterior housing of the antenna of the preferred embodiment.

FIG. 2 is a sectional view of the antenna shown in FIG. 1.

FIG. 3 is a sectional view taken along the lines 3-3 in FIG. 2.

FIG. 4 is an exploded view with parts removed of the antenna shown in FIGS. 2 and 3.

DESCRIPTION oF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1, which constitutes a preferred embodiment of the invention, an omni-directional receiving and transmitting antenna 10. While specific dimensions and components will be described in connection with an antenna designed for use on the ship to shore marine frequencies, it will be recognized that these dimensions areonly exemplary and if the antenna were to be used for other transmission frequencies, different dimensions may be utilized.

The omni-directional receiving and transmitting antenna 10 is mounted on a mast 12 by any .suitable mounting means. The mast 12 may then be mounted on a structure such as a boat or ship. A lead wire 14 is adapted to be connected to a'suit'able utilization device such as a transmitter/receiver (not shown).

- As can be seen from FIGS. 1 and 2, the exterior portion of the omni-directional transmitting and receiving antenna 10 is of two-piece construction havinga hemispheric-shaped outer shell 18 and a cover 20. Both the outer shell 18 and the cover 20 can be made of any suitable non-conductive material, such as plastic. The purpose of this cover is to protect the interior of the antenna from corrosive elements. In the preferred embodiment, the outer shell 18 is shaped in the form of a hollow hemisphere. The cover 20 comprises ABS copolymers. The use of ABS copolymers acts to shield the circuitry from both physical damage and corrosion;

however, other non-conductive covers and other shapes may be utilized. The lead wire 14 in the preferred embodiment comprises a 50 ohm coaxial cable. It has been found that for use on ship to shore radio communication on bandwidths 156 to 162 mhz, the 50 ohm coaxial lead wire in connection with the antenna of the preferred embodiment is most suitable.

Referring now to FIGS. 2 and 3, the omni-directional transmitting and receiving antenna comprises a nonconductive hollow outer shell 18. Placed within the hollow outer shell 18 is a first substantially circularly shaped conductive element 22. The first conductive element 22 is a basic gamma-match quarter-wave halo which includes a discontinuity 24 therein as can be clearly seen in FIG. 4. A second continuously circularly-shaped conductive element 26 is also located within the hollow outer shell 18 and is adjacent to and coaxial with the first conductive element 22. As can be seen clearly in FIGS. 3 and 4, the second conductive element 26 is a complete circle and does not contain any discontinuity. The second conductive element 26 is spaced apart from the first conductive element 22 by a preselected distance and this spacing may be maintained by any suitable spacing means such as a plurality of non-conductive spacer elements 28. The first conductive element 22 is a basic gamma-match quarterwave halo and acts to provide horizontal polarization. The second conductive element 26 provides a ground plane to effect vertical polarization for the antenna and, thus, the spacing between the first conductive element 22 and the second conductive element 26 is critical to provide maximum vertical polarization of the antenna. In the preferred embodiment, it has been found that a vertical spacing of 3/16 of an inch between the first conductive element 22 and the second conductive element 26 is preferable.

The first conductive element 22 is electrically connected to the second conductive element 26 by a conductor element 30. In the preferred embodiment, the conductor element 30 comprises a rigid conductive material and aids in maintaining the required spacing between the first conductive element 22 and the second conductive element 26. The conductor element 30 is connected by any suitable conductive connecting means, such as a screw or rivit, to the first conductive element 22 adjacentto the discontinuity 24 and is connected to the second conductor element 26 by suitable conductive conducting means 27 as shown in FIG. 3. It will be understood that while the conductor element 30 in the preferred embodiment is rigid, non-rigid conductors may also be used.

Referring again to FIGS. 2-4, it can be seen that the lead wire 14 is electrically connected to the first conductive element 22 and the second conductive element 26 by the use of conducting clips 32 and 34, respectively. The conducting clips 32 and 34 are connected to the conductive elements 22 and 26 in such a location so as to be located at the center frequency of the antenna. In the preferred embodiment of the invention, the center of the conducting clip 32 is located 2 it inches from the discontinuity 24 and the conducting clip 34 is located directly below the conductive clip 32. When, as in the preferred embodiment, the lead wire 14 comprises a coaxial cable, the center cable of the coaxial lead wire 14 is electrically connected to the first conductive element 22 by the conducting clip 32 and the shield 16 of the coaxial lead wire 14 is electrically connected to the second conductive element 26 by the conducting clip 34. While it has been shown that conducting clips 32 and 34 are utilized to electrically connect the lead wire 14 to the first and second conductive elements 22 and 26, respectively, it will be recognized that any manner for electrically connecting the lead wire may be utilized so long as the lead wire is firmly connected to the conductive elements 22 and 26.

After placing the above elements into the hollow outer shell 18, the remaining void within the outer shell 18 is filled with a polyurethane substance 36 to add support to the elements within and to provide for the rigid placement of these elements within the hollow outer shell 18. The basic ingredients for a suggested polyurethane substance comprises a polyurethane resin, and an iscyanatic urethane resin combined equally by weight. When hardened, this polyurethane has a dielectric constant of 1 and a dissipation factor of 0.005, thereby not affecting the signal appreciably. However, it will be recognized that the omnidirectional receiving and transmitting antenna 10 is operable without it. Lastly, after filling the void with the polyurethane substance 36, the cover 20 is placed over the opening and suitably fastened, thereby completing the construction of the antenna. The finished omnidirectional receiving antenna 10 is now completely self-enclosed and it is impervious to metallically corrosive elements such as salt water spray, rain, wind and other corrosive elements. Furthermore, by utilizing a first conductive element having a discontinuity therein electrically connected to a circularly-shaped second conductive element spaced therefrom the antenna is both horizontally and vertically polarized and is, therefore, not adversely affected by the rolling and tossing of a ship or boat on the high seas. For optimum performance, the antenna 10 should be mounted on a plane as near to vertical as possible, although minor deviations from this orientation will not deter the antennas operation.

It has been found that it is necessary that the first conductive element 22 and the second conductive element 26 be manufactured from the same conductive material. It has also been found that a hollow tubular conductive material is preferable. In the preferred embodiment, aluminum tubing having a 3/16 of an inch outer diameter has been found preferable. As can clearly be seen from FIG. 3, the first conductive element 22 has a radius equal to the radius of the second conductive element 26 and, therefore, it is necessary because of the discontinuity 24 contained within the first conductive element 22 that the length of the first conductive element 22 be slightly shorter than the length of the second conductive element 26. In the preferred embodiment, the first conductive element 22 is 19 inches long while the second conductive element 26 is 19 56 inches long, thereby making the discontinuity 24 A of an inch in length. For optimum results, the conductor element 30 should preferably be rigid and manufactured from the same material as the first conductive element 22 and the second conductive element 26 and, therefore, an aluminum tubing having a 3/16 inch outer diameter is used to manufacture the conductor element 30. Using the above lengths of material, the first conductive element 22 and the second conductive element 26 each have a diameter of 6 inches.

In order to obtain proper operation of the antenna, it is critical that the second conductive element 26 be closer in proximity to the opening in the hollow shell than is the first conductive element 22 containing the discontinuity 24 therein. In other words, when the antenna is mounted vertically as shown in FIG. 1, the first conductive element 22 will always be located above the second conductive element 26. Constructing an antenna utilizing the dimensions and materials described above will result in an omni-directional transmitting and receiving antenna which. is tuned for the ship to shore marine frequencies; i.e., 156 to 162 mhz. The antenna will provide a gain of 2 db over an isotropic antenna and will be both horizontally and vertically polarized. Whilespecific dimensions and components have been described, it will be recognized that these dimensions are only exemplary and that if the antenna were to be used with other frequencies, different lengths and different spacing between the conductive elements may be utilized and obviously, many modifications and alterations may be made herein without departing from the spirit and the scope of the invention as set forth in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An omni-directional marine band transmitting and receiving antennacomprising: v

a non-conductive hollow outer shell;

a first substantially circularly shaped tubular conducjacent to and coaxial with said first conductive element, wherein the radius of said second conductive element is equal to the radius of said first conductive element, wherein said first conductive element and said second conductive element comprise the same material and wherein said second conductive element is in closer proximity to the opening in said hollow shell than said first conductive element;

a rigid means for electrically connecting said first conductive element to said second conductive element wherein said rigid means is connected to said first conductive element adjacent to said discontinuity;

a coaxial lead wire for connecting said antenna to a utilization device, wherein the center cable of said lead wire is electrically connected to said first conductive element and wherein the shield of said lead wire is electrically connected to said second conductive element;

a polyurethane substance placed within said hollow shell whereby said first and second elements are immobilized; and

a non-conductive cover means for sealing the opening of said hollow shell thereby making said antenna impervious to corrosive elements. 2. The antenna of claim 1 wherein said first conductive element comprises a l9 inch tubular aluminum;

conductor, wherein saidsecond conductive element comprises'a l9 55 inch tubular aluminum conductor, and wherein said second aluminum conductor is-spaced 3/16 of aninch from said first aluminum conductor.

' n a: :k :k 

1. An omni-directional marine band transmitting and receiving antenna comprising: a non-conductive hollow outer shell; a first substantially circularly shaped tubular conductive element located within said outer shell and wherein said first conductive element contains a discontinuity therein; a second continuous circularly shaped tubular conductive element located within said outer shell adjacent to and coaxial with said first conductive element, wherein the radius of said second conductive element is equal to the radius of said first conductive element, wherein said first conductive element and said second conductive element comprise the same material and wherein said second conductive element is in closer proximity to the opening in said hollow shell than said first conductive element; a rigid means for electrically connecting said first conductive element to said second conductive element wherein said rigid means is connected to said first conductive element adjacent to said discontinuity; a coaxial lead wire for connecting said antenna to a utilization device, wherein the center cable of said lead wire is electrically connected to said first conductive element and wherein the shield of said lead wire is electrically connected to said second conductive element; a polyurethane substance placed within said hollow shell whereby said first and second elements are immobilized; and a non-conductive cover means for sealing the opening of said hollow shell thereby making said antenna impervious to corrosive elements.
 2. The antenna of claim 1 wherein said first conductive element comprises a 19 3/8 inch tubular aluminum conductor, wherein said second conductive element comprises a 19 1/2 inch tubular aluminum conductor, and wherein said second aluminum conductor is spaced 3/16 of an inch from said first aluminum conductor. 